Method of sewing parallel rows of zigzag stitches



April 4, 1961 5 SCHENKENGEL 2,977,913

METHOD OF SEWING PARALLEL ROWS 0F ZIG-ZAG STITCHES Filed Feb. 15, 1957F/GB A TEE/V5) METHOD OF SEWING PARALLEL ROWS OF ZIG- ZAG STITCHESEmerich Schenkengel, Kaiserslautern, Pfalz, Germany, assignor to G. M.Pfaif A.G., Kaiserslautern, Pfalz, Germany, a corporation of GermanyFiled Feb. 13, 1957, Ser. No. 640,035 Claims priority, applicationGermany Feb. 17, 1956 5 Claims. (Cl. 112-264) The present inventionrelates to an improved method of and means for sewing parallel rows orlines of zig-Zag stitches by the aid of zig-zag sewing machines, such asrequired in the sewing of button holes, ornamental designs, etc.including at least one pair of parallel rows or lines of zig-zagstitches or patterns.

While the invention will be described in the following with specificreference to the sewing of button holes, it will be evident that theimproved features and steps may be used with equal advantage inconnection with other sewing operations involving the production of twoor more rows of zig-zag lock stitches.

Conventional zig-zag stitch button hole sewing machines, as described,for instance, by US. Patent Nos.

' hole stitch-es,

If the lines of zig-zag stitches of a button hole'of this I type areproduced in the usual manner by first sewing one row of zig-zag sidestitches in one direction and subsequently sewing the adjacent row ofside stitches in the opposite direction, uponreversal of the stitchingdirection and lateral displacement of the middle stitching position orline, it is found that the reverse stitching line or pattern, whilemarked by its exact parallelism with the forward stitches is lessperfect and satisfactory from an appearance point of view compared withthe forward stitches, thereby distinguishing button holes fabricatedmechanically by machines from manually sewn button holes which arecharacterized by the uniformity of the structure and appearance of bothside stitches.

One method to avoid the above-mentioned disadvantage consists inreversing the work or material by 180 upon completion of the firstzig-zag side stitch, a procedure being highly cumbersome andimpractical, especially in caseof relatively large work pieces or sizesof sewing material. i t

Another method to overcome the above-mentioned difficulty consistsinlifting the work clamp or presser foot upon completion ofgthe first.zig-zag side stitch and to pull back the work to the starting" point ofthesecond side stitch to be sewn parallel to and in the same directionas the first side stitch of the button hole. This solution again resultsin an'impairrnent'of the appearance of the stitches or final buttonholeas well as in other difficulties i Accordingly, an object. of thepresent invention is'the: provision of an improved method 0f and meansfor pro-' 2,977,913 Patented Apr. 4, 1961 ducing parallel rows or linesof zig-zag stitches by means of zig-zag sewing machines, whereby theabove and related difficulties and drawbacks are substantially avoided.

Another object of the invention is the provision of an improvedmethod-of and means for producing parallel rows or lines of zig-zagstitches, whereby the individual lines are characterized both by anexact parallelism as well as by an equal structure and appearance of thestitches. 7

Yet another object of the invention is the provision of a novel methodof and means to enable the fabrication of parallel zig-zag stitcheswithout displacement of the work and the additional labor and otherdisadvantages connected therewith.

Still another object of the invention is the provision of presser footguide means for use in connection with a zig-zag sewing machine forcarrying into effect the method according to the invention, especiallyfor the sewing of raised zig-zag stitches in the fabrication of buttonholes and the like. 7

The invention, as to its further objects and novel aspects, will bebetter understood from the following detailed description taken inreference to the accompanying drawing, forming part of thisspecification and wherein:

Figs. 1' to 4 are diagrammatic representations of stitchesproducedduring the successive steps of the improved method according to theinvention; and 7 Figs. 5 and 6 are elevational and bottom views,respectively, of an improved presser foot construction being especiallysuitable in the fabrication of button holes comprising raised zig-zagstitches made by the method according to the present invention. 7

With the foregoing objects in view, the improved method according to theinvention, with specific reference to the sewing of button holes,involves generally the stepsof sewing a first zig-zag side stitch in onedirection, such as the foreward operating direction of the machine,laterally displacing the stitching position or medial stitching line bya distance equal to the required spacing distance between the parallelside stitches of the button hole and subsequently sewing a line ofstraight stitches in the opposite or reverse direction of the machineand in parallel to the first line or row ofside stitches. As a result,the needle, upon completion of the straight stitches or seam will be ina position for starting the sewing of the second line of zig zag sidestitches in the same direc-.

tion and parallel to the first line of side stitches of the button holeduring the third or final step of the buttonhole sewing cycle oroperation. In other words, the second line of zig-zag side stitches issymmetrical to and overlies the seam or line of straightstitchesproduced during the reverse operation of the machine. This not onlyinsures a perfect parallelism between the side stitches of the buttonhole, but furthermore results in a uniformity of both side stitches bothas to structure and appearance. Practice has shown that a line ofzig-zag stitches sewn over a' line of straight stitches does notvisiblydiffer from a simple line of zig-zag stitches sewn .withoutunderlying straight stitches, provided ordinary thread is used for boththe straight and zig-zag stitches; After both side stitches have beencompleted, the material between the closely adjoining stitches is slitby the operation of the button hole cutting mechanism in the usualmanner. The ends of the side stitches may be joined by barring zig-zagstitches of greater width extending across both side stitches, in amanner described in greater detail hereafter. j

While sewing the secondside stitch, it is necessary to pass thepreviously completed first side stitch underneath the 'presser foot orwork;.clamp of the machine. In order to facilitate this operation and toproperly guide the 'work, especially when producing raised stitches or 3patterns characterized by their pleasing appearance, the presser foot,according to an improved feature of the invention, is provided withsuitable guide grooves constructed in such a manner as to properly guidethe stitches, substantially without interference with the stitch formingoperation of the machine.

It has already been proposed to provide a single guide groove in theunderface of the presser foot base of a zigzag sewing machine, saidgroove being subdivided into two shorter grooves or sections close tothe needle aperture within said base and said shorter sections beingseparated from-one another by a central rib or ridge medial to theundivided main section of the groove. Such a presser foot constructionis limited in its use to zig-zag sewing machines having a fixed needleposition and is unsuitable for use with machines equipped withadjustable needle position as required for the sewing of parallel scamsor stitches of either straight or zig-zag shape in carrying into effectthe present invention.

The improved presser foot construction according to the presentinvention substantially overcomes the aforementioned difficulties anddefects, whereby to enable the fabrication of both fiat and raisedzig-zag stitches or patterns, the latter being especially desirable inthe sewing of button holes on account of their better appearance.

To this end, the improved presser foot construction according to theinvention comprises essentially a pair of parallel guide groovesextending over the entire width of the base of the foot and beingseparated by a central rib or ridge medial to or concentric, accordingto a preferred construction, with the needle aperture within said base.Furthermore, said ridge has a height extending to a point spaced fromthe bottom or underside of said base, to prevent interference with theoperation of the stitch forming mechanism of the machine by allowing thelower thread cooperating with the upper thread in the formation of thelock stitches to be readily extracted or withdrawn, to produce a raisedstitching pattern or button hole. In this manner, zig-zag sewingmachines having means for adjusting the stitching position may bereadily and simply adapted for the sewing of button holes of either theflat or raised type in accordance with the novel method proposed by thepresent invention.

Referring more particularly to the drawing, Figs. 1 to 4, illustratingthe method according to the invention, the numeral 1 diagrammaticallyshows the first line of zig-zag side stitches of a button hole sewn inthe forward operating direction of the machine as indicated by the arrowa, during the first step of a complete button hole sewing cycle oroperation' Numeral 2 indicates the straight stitch or seam sewn in thereverse direction as indicated by the arrow b upon completion of thefirst stitch 1 and lateral shift of the stitching position by a distanced equal to the distance between the medial lines of the final stitchesof the completed button hole, Fig. 4. To this end, the machine, uponcompletion of the first zig-zag stitch 1, is adjusted or converted fromzig-zag to straight stitching, this operation as well as the change ofthe stitching position being carried out either manually orautomatically by means well known and readily understood, as shown bythe above-mentioned patents. Upon completion of the straight seam 2, the

needle is in a position adjacent to the beginning of the line of sidestitches 1, that is, ready to start the third step of sewing the secondparallel line of zig-zag side stitches 4 of the button hole in the sameor forward direction a as used in sewing the line of stitches 1. Forthis purpose, the direction of operation of the machine is againreversed at the end of the straight stitch 2. The zig-Zag stitch 4 isthus superimposed upon or overlies the straight seam 2, whereby bothside zig-zag stitches 1 and 4- of the button hole'are sewn in the samedirection, to result in an exact parallelis'rn'as well as an equalstructure and appearance of the stitches, substantially. without thedrawbacks and defects of previously known stitching methods andoperations. In Fig. 2, the side stitch 4 is shown only partly completed,the complete stitch being shown in Fig. 4.

The ends of both side, stitches 1 and 4 may be joined by barring zig-zagstitches 3 and 5 of greater width and extend across both rows of sidestitches, as shown in? Figs. 3 and 4, the former illustrating thebarring stitch produced at the completion of the straight stitch 2 and.

prior to the starting of the line of side stitches 4 and Fig. 4 showingthe barring stitch sewn at the completion of the line of side stitches4, to result in a final button hole upon slitting of the narrow spacebetween the stitches 2 and 4, shown on an exaggerated scale in thedrawing, by the button hole cutting mechanism.

As pointed out, the steps of the invention may be carried out manuallyby the operation the means controlling the sewing direction and zerostitch position, as well as for changing from straight to zig-zagstitching, and for adjusting the width of the zig-zag stitches, allknown'per se in connection with conventional zig-zag, as shown by theabove-mentioned U.S. patents.

As will be evident, the method of the invention may also be carried intoeffect mechanically by theuse of a sewing machine equipped with meansfor automatic stitch position and stitch width control. In machines ofthis type, the controls are effected by suitable control devices, suchas cams etc., a separate control device being provided, for instance, tocontrol the stitch width and stitch position, respectively.Alternatively, a single control device may be employed in anautomatically controlled zig-zag sewing machine constructed in a knownmanner to effect control of both the width and position of the stitches.

More particularly, in the case of button hole sewing machines havingautomatic means to control the entire operating cycle or button holesewing operation by means of a cam or the like, the cam initiating thecontrolling impulses or operations may be so constructed that, after thesewing of the first line of side stitches, a straight seam is sewn inthe opposite direction upon laterally shifting of the stitch position,whereupon the sewing direction is again reversed to initiate the sewingof the second line of side stitches, in the manner described and readilyunderstood from the foregoing. The control cam or the like mayfurthermore be so constructed as to increase the stitch width at the endof the straight seam 2 and zig-zag stitch 4, respectively, to enable thesewing of the barring stitches 3 and 5 at the opposite ends of thebutton hole. For this purpose, further provision may be made to effect astitch position control, either manually orautomatically to cause thebarring stitches 3 and 5 to be symmetrical to the medial line of theside stitches 2 and 4 or extend across both ends of the side stitches.

Figs. 5 and 6 show the improved presser foot construction for use inzig-zag sewing machines having means for stitch position control andadapted for practicing the method according to the invention. Thepresser foot shown, being of conventional construction, comprises anupper. vertical part 6 having an extension 7 for mounting it upon thepresser foot bar of the machine. The lower part or base 3 engaging thework in the lowered position has an aperture 11 providing a passagewayfor the needle indicated at 14'. Provided at the bottom or undersurface13 of the base 8, in accordance with the improved construction of thepresent invention, are a pair of parallel guide grooves 9 and 10extending across said base and being spaced by a separating rib or ridge12 the ridge 12 separating the grooves 9 and 10 has the effect ofpreventing interference with the stitching operation of the needle andcooperating stitch forming tools of the machine, whereby to enable thesewing of raised stitches by extraction or ready withdrawal of the lowerthread, without interference with the stitch formation and impairment ofthe structure and appearance of the stitches.

In the foregoing'the invention has been described with reference to aspecific illustrative methodrand device. It will be evident, however,that variations and modifications, as well the substitution ofequivalent steps and elements for those shown and disclosed forillustration,

may be made without departing from the broader scope and spirit of theinvention, as set forth in the appended claims. The specification anddrawing are accordingly to be regarded in an illustrative rather than ina limiting sense.

I claim: 1

1. A method of producing parallel zig-zag stitches by a zig-zag sewingmachine having means to reverse the stitching direction, to control themiddle stitch position and to convert from zig-zag to straight stitchingand vice versa, said method comprising the sequential steps of sewing afirst line of zig-zag stitches in a predetermined direction, sewing aline of straight stitches in a direction opposite to said predetermineddirection and in spaced relation and parallel to said first stitchingline, and sewing a third line of zig-zag stitches in said predetermineddirection symmetrical to and overlying said straight stitching line. 7

2. A method of sewing button holes by the aid of zig-zag sewing machineshaving means to reverse the stitching direction, to control the middlestitch position and to convert from zig-zag to straight stitching andvice versa, said method comprising the sequential steps of sewing afirst line of zig-zag side stitches in a first direction, sewing a lineof straight stitches in a direction opposite to said first direction,and parallel to and spaced from the middle line of said first stitches,sewing a second line of button hole zig-Zag side stitches in said firstdirection and symmetrical to and overlying said straight stitches, andcutting the intervening material between said first and second lines ofzig-zag stitches.

3. A method of sewing button holes of the air of zigzag sewing machineshaving means to reverse the stitching direction, to control the zigzagwidth and middle stitch position and to convert from zig-zag to straightstitching and vice versa, said method comprising the sequential steps ofsewing a first line of zig-zag side stitches of predetermined width in afirst direction, sewing a line of straight stitches in a directionopposite to said first direction and parallel to and spaced from saidfirst stitching line, producing a barring zig-Zag stitch of greaterwidth than said side stitches at the beginning of said first line ofside stitches, sewing a second line of zigzag side stitches in saidfirst direction of a width equal to said predetermined width andsymmetrical to and overlying said straight stitches, and producing abarring zigzag stitch at the end of said second row of zig-zag sidestitches.

4. A method as claimed in claim 3 said steps of producing barringstitches consisting in sewing zig-zag stitches between the outer edgesof said first and second line of zig-Zag side stitches.

5. A method of sewing button holes by the aid of zig-zag sewing machineshaving means to reverse the stitching direction, to control the zigzagwidth and middle stitch position and to convert from zig-zag to straightstitching and vice versa, said method comprising the sequential steps ofsewing a first line of zig-zag side stitches of predetermined width andlength and in a predetermined direction, sewing a line of equal lengthof straight stitches adjacent to said first stitches and in a directionopposite to said predetermined direction and parallel to and spaced fromsaid first stitches, producing a first barring zig-zag stitch of greaterwidth than and located at the beginning of said first stitches, sewing asecond line of button hole zig-zag side stitches in said first directionsymmetrical to and overlying said straight stitches, producing a secondbarring zig-zag stitch at the end of said second button hole stitches,said barring stitches extending across the ends of said button holestitches, and cutting the intervening material between said first andsecond button hole stitches.

References Qited in the file of this patent UNITED STATES PATENTS786,934 Woodward Apr. 11, 1905 1,427,197 Egan Aug. 29, 1922 1,483,184McCann Feb. 12, 1924 1,640,283 Miller Aug. 23, 1927 1,675,508 MullerJuly 3, 1928 1,699,314 Sieber Jan. 15, 1929 2,151,381 Goldsmith Mar. 21,1939 2,378,534 Beyer June 19, 1945 2,682,845 Casas Robert et a1. July 6,1954

